KR20120023746A - Copper foil composite - Google Patents

Abstract

Provided is a copper foil composite having improved workability. As a copper foil composite body which laminates copper foil and a resin layer, the breaking strain of copper foil is 5% or more, the thickness (t) of copper foil, the stress (f) of copper foil in 4% of tensile strain, and a resin layer When (FxT) / (fxt)> 1 is satisfied when it is set as the thickness (T) of the resin layer and the stress (F) of the resin layer in 4% of tensile strain.

Description

Copper foil composites {COPPER FOIL COMPOSITE}

The present invention relates to a copper foil composite material suitable as an electromagnetic shielding material, a copper laminate for FPC, and a substrate requiring heat dissipation.

The copper foil composite which laminates copper foil and a resin film is used as an electromagnetic shielding material (for example, patent document 1). Copper foil has electromagnetic shielding property, and a resin film is laminated | stacked for reinforcement of copper foil. As a method of laminating | stacking a resin film on copper foil, the method of laminating a resin film to copper foil with an adhesive agent, the method of depositing copper on the resin film surface, etc. are mentioned. In order to ensure electromagnetic shielding property, since the thickness of copper foil needs to be several micrometers or more, the method of laminating a resin film on copper foil is inexpensive.

Moreover, copper foil is excellent in electromagnetic shielding property and can shield the whole surface of a shielded body by covering a shielded body. On the other hand, in the case where the shielded body is covered with braided copper or the like, the shielded body is exposed in the net portion and the electromagnetic shielding property is inferior.

In addition to the electromagnetic shielding material, a composite of a copper foil and a resin film (PET, PI (polyimide), LCP (liquid crystal polymer), etc.) is used for FPC (flexible printed circuit board). In particular, in FPC, PI is mainly used.

The FPC may be deformed like bending or bending, and an FPC having excellent bendability has been developed and employed in a mobile phone or the like (Patent Document 2). Usually, the bending and bending which FPC receives in a bending part are bending deformation of one direction, and are simple compared with the deformation | transformation when the electromagnetic shielding material wound on an electric wire etc., and the FPC composite did not require much workability.

Japanese Laid-Open Patent Publication No. 7-290449 Japanese Patent Publication No. 3009383

By the way, although a copper foil composite body may be used as a shielding material by winding it to the outer side of shielded bodies, such as a cable, since copper foil is easy to tear or produce a crack, it was difficult to use it for the use which requires bending and bendability. Moreover, workability may be calculated | required also in a copper foil composite for FPC depending on an installation place.

Moreover, when the thickness of copper foil is thick, elongation improves, but when it is thin, there exists a characteristic that ductility falls extremely. On the other hand, when copper foil is thickened, since rigidity becomes high, there exists a problem that the shielding process which winds a copper foil composite to shielded bodies, such as an electric wire, becomes difficult, for example. In short, it is difficult to achieve both the flexibility and the workability of the copper foil composite.

Therefore, the objective of this invention is providing the copper foil composite which improved the workability.

MEANS TO SOLVE THE PROBLEM The present inventors discovered that bendability can be improved without impairing workability by defining the thickness and distortion of the copper foil and resin layer which comprise a copper foil composite_body | complex, and came to this invention.

That is, the copper foil composite of this invention is made by laminating | stacking a copper foil and a resin layer, and the breaking strain of the said copper foil is 5% or more, and the said in thickness (t) of the said copper foil and 4% of tensile strain. (F × T) / (f × t) ≧ 1 when the stress (f) of the copper foil, the thickness (T) of the resin layer, and the stress (F) of the resin layer in the tensile strain 4% are set. Satisfy.

It is preferable that the breaking strain of the said copper foil composite_body is 30% or more.

It is preferable to satisfy (F × T) ≦ 3.1 (N / mm).

The copper foil is 200? In total at least one selected from the group consisting of Sn, Mn, Cr, Zn, Zr, Mg, Ni, Si, and Ag. It is preferable to contain 2000 mass ppm.

According to this invention, the copper foil composite which improved the workability can be obtained.

The copper foil composite of the present invention is obtained by laminating a copper foil and a resin layer.

<Copper gourd>

The breaking strain of copper foil is made into 5% or more. If the breaking strain is less than 5%, even if (F × T) / (f × t) ≧ 1 of the copper foil composite described later is satisfied, the elongation of the copper foil composite decreases. As long as (FxT) / (fxt)> 1 is satisfied, the breaking strain of copper foil is so preferable that it is large.

Since the shield performance improves with the thing with the electroconductivity of copper foil being 60% IACS or more, it is preferable that purity is high as a composition of copper foil, Preferably, purity is 99.5% or more, More preferably, it is 99.8% or more. . Preferably the rolled copper foil which is excellent in bendability is good, but an electrolytic copper foil may be sufficient.

Other elements may be contained in copper foil, and the sum total content of these elements and an unavoidable impurity should just be less than 0.5 mass%. In particular, in the copper foil, at least 1 type selected from the group of Sn, Mn, Cr, Zn, Zr, Mg, Ni, Si, Ag is 200? When it contains 2000 ppm, since elongation improves rather than pure copper foil of the same thickness, it is preferable.

Moreover, in the case of an electromagnetic shielding material use, the thickness t of copper foil is 4? It is preferable to set it as 12 micrometers. When thickness t is less than 4 micrometers, while shielding property and breaking strain fall, it may become difficult to handle when manufacturing copper foil and laminating | stacking with a resin layer. On the other hand, the one where the thickness t is thicker increases the breaking strain. However, when the thickness t exceeds 12 µm, the rigidity is increased and workability may decrease. Moreover, when thickness t exceeds 12 micrometers, (F * T) / (f * t) ≥1 of the copper foil composite_body | complex mentioned later does not satisfy | fill, and it exists in the tendency for the fracture strain of a copper foil composite to fall rather. . In particular, when the thickness t exceeds 12 μm, it is necessary to thicken T in order to satisfy (F × T) / (f × t) ≥ 1, and when (F × T) exceeds 3.1, have.

On the other hand, when using it for the board | substrate for FPC or heat dissipation, thickness (t) of copper foil is 4? It is preferable to set it as 40 micrometers. In the case of a substrate requiring FPC or heat dissipation, since flexibility is not required for the copper foil composite in comparison with the electromagnetic shielding material, the maximum value of the thickness t can be 40 m. Moreover, when using PI as a resin layer, since PI intensity is high, even if thickness t of copper foil is thick, (F * T) / (f * t) ≧ 1 can be satisfied. In addition, the board | substrate which requires heat dissipation is used, without making a circuit in the copper foil of FPC, making copper foil adhere to a heat-radiating body.

<Resin layer>

Although it does not restrict | limit especially as a resin layer, Although a resin material may be apply | coated to copper foil and a resin layer may be formed, the resin film which can be affixed on copper foil is preferable. As a resin film, PET (polyethylene terephthalate) film, PI (polyimide) film, LCP (liquid crystal polymer) film, PP (polypropylene) film is mentioned, Especially PET film can be used preferably. In particular, strength can be raised by using a biaxially stretched film as a PET film.

Although the thickness (T) of a resin layer is not specifically limited, In the case of an electromagnetic shielding material use, it is normally 7? It is about 25 micrometers. When thickness T is thinner than 7 micrometers, the value of (F * T) mentioned later will become low, and (F * T) / (f * t) ≥ 1 will not be satisfied, and the (stretching) fracture strain of a copper foil composite will be It tends to be lowered. On the other hand, even if thickness T exceeds 25 micrometers, the (stretching) breaking strain of a copper foil composite tends to fall, and (FxT) may especially exceed 3.1.

As a lamination | stacking method of a resin film and copper foil, an adhesive agent may be used between a resin film and copper foil, and a resin film may be thermocompression-bonded to copper foil without using an adhesive agent. However, it is preferable to use an adhesive agent from the point which does not apply extra heat to a resin film. It is preferable that the thickness of an adhesive bond layer is 6 micrometers or less. When the thickness of an adhesive bond layer exceeds 6 micrometers, after laminating to a copper foil composite_body | complex, it will become easy to break only copper foil.

On the other hand, when used for the board | substrate for FPC or requiring heat radiation, the thickness T of a resin layer is 7? It is about 70 micrometers. When thickness T is thinner than 7 micrometers, the value of (F * T) mentioned later will become low and it will not satisfy (F * T) / (f * t) ≥1, and the (stretching) fracture strain of a copper foil composite will It tends to be lowered. On the other hand, when using PI as a resin layer, since PI can improve adhesiveness compared with PET, even if it exceeds (FxT) = 3.1, ductility does not fall especially.

In addition, when a resin layer and an adhesive bond layer can be distinguished and these can be isolate | separated, F and T of the "resin layer" of this invention say the value of the resin layer except an adhesive bond layer. However, when distinguishing between a resin layer and an adhesive bond layer is possible, only copper foil may be melt | dissolved from a copper foil composite, and you may measure as a "resin layer" including an adhesive bond layer. This is because the resin layer is usually thicker than the adhesive layer, and even if the adhesive layer is included in the resin layer, the values of F and T may not be significantly different as compared with the case of only the resin layer.

In the case of FPC, although a coverlay film is affixed and both surfaces of copper foil may become a resin layer, in this case, F and T of a resin layer shall add the strength and thickness of a coverlay powder.

Moreover, you may form Sn plating layer about 1 micrometer thickness in order to improve corrosion resistance (salt resistance) on the surface opposite to the formation surface of the resin layer in copper foil.

Moreover, in order to improve the adhesiveness of a resin layer and copper foil, you may give surface treatment, such as a roughening process, to copper foil. As this surface treatment, it is described in Unexamined-Japanese-Patent No. 2002-217507, Unexamined-Japanese-Patent No. 2005-15861, Unexamined-Japanese-Patent No. 2005-4826, 7-32307, etc., for example. We can adopt thing which there is.

MEANS TO SOLVE THE PROBLEM The present inventors discovered that bendability can be improved, without impairing workability by defining the thickness and distortion of the copper foil and resin layer which comprise a copper foil composite_body | complex.

That is, when it is set as the thickness (t) of copper foil, the stress (f) of the copper foil in 4% of tensile strain, the thickness (T) of the resin layer, and the stress (F) of the resin layer in 4% of tensile deformation. The copper foil composite which satisfies (FxT) / (fxt) ≥ 1 has been found to have high ductility and improve bendability.

Although the reason is not clear, (FxT) and (fxt) both show stress per unit width (for example, (N / mm)), and the copper foil and the resin layer are laminated to have the same width. (FxT) / (fxt) has shown the ratio of the force applied to the copper foil and resin layer which comprise a copper foil composite from the point which has. Therefore, when this ratio is one or more, more force is added to the resin layer side, and the resin layer side becomes stronger than copper foil. Since copper foil is easy to be influenced by a resin layer by this, and copper foil becomes uniformly stretched, it is thought that the ductility of the whole copper foil composite_body also increases.

Here, F and f should just be a stress in the same amount of deformation after plastic deformation, but the tensile strain 4 in consideration of the breaking strain of copper foil and the deformation which plastic deformation of a resin layer (for example, PET film) starts. It is made into% stress. In addition, the measurement of F can be performed by the tensile test of the copper foil which remained after removing the resin layer from the copper foil composite_body | complex with a solvent. Similarly, f can be measured by the tensile test of the resin layer which removed the copper foil from the copper foil composite_body | complex by acid etc. In the case where the copper foil and the resin layer are laminated via the adhesive, when the adhesive layer is removed by a solvent or the like during the measurement of F and f, the copper foil and the resin layer are peeled off and the tensile test is performed separately from the copper foil and the resin layer. Can be used for T and t can measure the cross section of a copper foil composite body by observing with various microscopes (optical microscope etc.).

Moreover, when the values of F and f of the copper foil and resin layer before manufacturing a copper foil composite are already known, the heat treatment which changes the characteristic of a copper foil and a resin layer largely when manufacturing a copper foil composite is not performed. If not, the above known F and f values before the copper foil composite is produced may be employed.

As described above, by satisfying (F × T) / (f × t) ≧ 1 of the copper foil composite, the ductility of the copper foil composite is increased, and the breaking strain is also improved. Preferably, when the breaking strain of the copper foil composite is 30% or more, the copper foil composite is wound around the outside of shielded bodies such as cables to form a shielding material, and then cracks are generated when the copper foil composite is bent along with the circumference of the cable. This does not happen well.

Here, the value of the breaking strain of the copper foil composite is that when the copper foil and the resin layer are broken at the same time by a tensile test, the deformation is adopted. Adopt a variant.

When (FxT)? 3.1 (N / mm) is satisfied, the rigidity of the resin layer is lowered, and the workability of the copper foil composite is improved. Moreover, since copper foil and PET do not peel easily, and ductility of a composite improves, when a copper foil composite is wound and bent to a cable etc., a crack does not arise easily. On the other hand, when (F × T) exceeds 3.1 (N / mm), not only the rigidity of the resin layer is increased, but also the strength of the resin layer is increased, so that when the strain such as tensile or bending is applied to the copper foil composite, It is easy to peel from copper foil, and the breaking strain of a composite may fall.

Example

1. Electromagnetic shielding material

<Production of Copper Foil Composite>

After the tough pitch copper ingot was hot rolled and the oxide was removed by surface cutting, the cold rolling, annealing and pickling were repeated to thin down to a predetermined thickness, and finally annealing was performed to obtain a copper foil having workability. Tension at the time of cold rolling and the rolling reduction conditions of the width direction of a rolling material were made uniform so that copper foil might become a uniform structure in the width direction. In the next annealing, temperature management was performed using a plurality of heaters so as to have a uniform temperature distribution in the width direction, and the temperature of copper was measured and controlled. To some copper ingots, a predetermined amount of Sn or Ag was added to obtain a copper foil.

A commercially available biaxially stretched PET film having a predetermined thickness was affixed to the copper foil with a urethane-based adhesive having a thickness of 3 µm to prepare a copper foil composite.

〈Tensile test〉

Plural tensile test pieces having a rectangular shape having a width of 12.7 mm were produced from the copper foil composite. Moreover, some of these tensile test pieces were immersed in solvents, such as ethyl acetate, the adhesive bond layer was melt | dissolved, the PET film and copper foil were peeled off, and the test piece which is only PET film and the test piece which is only copper foil, respectively was obtained.

The tensile test was performed under conditions of a gauge length of 100 mm and a tensile speed of 10 mm / min, and the average value of N10 was employed as the values of the strength (stress) and the elongation.

<Foldability of Copper Foil Complex>

The copper foil composite was wound around the outside of a cable having a diameter of 5 mm and a diameter of 2.5 mm, respectively, to prepare a shield wire with a vertical length. This shield wire was bent once at ± 180 ° and a bending radius of 2.5 mm, and the cracks of the copper foil composite were visually determined. The thing without a crack in a copper foil composite was made into (circle).

In addition, a vertically-attached shield wire means what wound the copper foil composite longitudinal direction along the axial direction of a cable.

<Processability of Copper Foil Composite>

When the above-mentioned vertical shielding wire was produced, the thing which was easy to wind a copper foil composite was made into (circle).

2. Copper foil composite for FPC

<Production of Copper Foil Composite>

After the tough pitch copper ingots were hot rolled and the oxides were removed by surface cutting, cold rolling, annealing and pickling were repeated to thin down to a predetermined thickness, and finally annealing was performed to obtain a copper foil having workability. Tension at the time of cold rolling and the rolling reduction conditions of the width direction of a rolling material were made uniform so that copper foil might become a uniform structure in the width direction. In the next annealing, temperature management was performed using a plurality of heaters so as to have a uniform temperature distribution in the width direction, and the temperature of copper was measured and controlled. To some copper ingots, a predetermined amount of Sn or Ag was added to obtain a copper foil.

The general surface treatment used by CCL was given to the copper foil surface. As a treatment method, what is described in Unexamined-Japanese-Patent No. 7-3237 was employ | adopted. After surface treatment, the PI layer which is a resin layer was laminated | stacked on copper foil by the lamination method, and CCL was produced. In addition, when laminating | stacking a PI layer on copper foil, although the thermoplastic PI type adhesive layer was interposed, this adhesive layer and PI film were included as the resin layer.

〈Tensile test〉

Plural tensile test pieces having a rectangular shape having a width of 12.7 mm were produced from the copper foil composite. Moreover, some of these tensile test pieces were immersed in the solvent (TPE3000 by Toray Engineering), the adhesive bond layer and PI film were dissolved, and the test piece only copper foil was obtained. Some test pieces were melt | dissolved copper foil with ferric chloride, etc., and the test piece only PI was obtained.

The tensile test was carried out under conditions of a gauge length of 100 mm and a tensile speed of 10 mm / min, and the average value of N10 was employed as the values of strength (stress) and elongation.

<Processability of Copper Foil Composite>

The crack which did not generate | occur | produce in copper foil by (circle) Nippon Shin-Kyokai technical standard JCBA T307) of bending radius (R) = 0mm was made into (circle), and the cracked thing was made into x.

The results obtained for the electromagnetic shielding material are shown in Table 1, and the results obtained for the copper foil composite for FPC are shown in Table 2.

As is apparent from Table 1, Example 1? In the case of 12, (F × T) / (f × t) ≥ 1 was satisfied, and both the bendability and workability of the copper foil composite were satisfactory. However, Example 1? (F x T) exceeding 3.1 (N / mm)? In the case of 3, although the bendability when winding up to the cable of diameter 2.5mm deteriorated, the bendability with respect to the cable of diameter 5mm is favorable, and sufficient practicality is acquired according to a use. In addition, in the case of Example 4 in which the breaking strain of the copper foil composite was less than 30%, the bendability when the coil was wound around a 2.5 mm diameter was deteriorated, but the bendability to the cable having a diameter of 5 mm was good, depending on the application. Sufficient practicality is obtained.

In addition, in the case of each Example except Example 4, the breaking strain of a copper foil composite_body is all 30% or more, and the ductility of a copper foil composite is excellent.

Moreover, when the shielding wire which attached the copper foil composite_body | complex of each Example longitudinally was bent repeatedly at the bending radius of +/- 90 degree and 30 mm, and the bending test was done, it was excellent in flexibility also compared with the comparative example.

On the other hand, in the case of the comparative example 1 using the copper foil whose breaking strain is less than 5%, since the intensity | strength of copper foil fell, stress (f) could not be measured and bendability also deteriorated.

Moreover, the comparative example 2 which (F * T) / (f * t) is less than 1? In the case of 5, although the copper foil whose breaking strain was 5% or more was used, the breaking strain of the copper foil composite_body became 20% or less, and bending property deteriorated.

In addition, Comparative Example 1? In the case of 5, the breaking strain of the copper foil composite was less than 30% in all, and the ductility of the copper foil composite was inferior.

As is apparent from Table 2, Example 13? Also in the case of 24, (F × T) / (f × t) ≥ 1 was satisfied, and the workability of the copper foil composite was good.

Also, Example 13? 24 is 30% or more in all the breaking strains of the copper foil composite, and is excellent in the ductility of the copper foil composite.

On the other hand, Comparative Example 6? In the case of 9, although (FxT) / (fxt) is less than 1, although the copper foil whose breaking strain is 5% or more was used, the breaking strain of a copper foil composite body becomes 20% or less, and workability deteriorates. It became.

In addition, Comparative Example 6? In the case of 9, the breaking strain of the copper foil composite was all less than 30%.

Claims (4)

As a copper foil composite formed by laminating a copper foil and a resin layer,
The breaking strain of the said copper foil is 5% or more,
In the thickness (t) of the said copper foil, the stress (f) of the said copper foil in 4% of tensile strain, the thickness (T) of the said resin layer, and the stress (F) of the said resin layer in 4% of tensile deformation. The copper foil composite which satisfies (F x T) / (f x t)? The method of claim 1,
The copper foil composite whose breaking strain of the said copper foil composite is 30% or more. The method according to claim 1 or 2,
Copper foil composite material which satisfy | fills (F * T) <3.1 (N / mm). The method according to any one of claims 1 to 3,
The copper foil is at least 200? Copper foil composite containing 2000 mass ppm.